The invention relates to a method of positioning a part and on a device for carrying out the method wherein operation of an electric motor drive is controlled in accordance with a nominal position of the part. It is generally known prior art to detect mechanical end stops by limit switches in a positioning device. When a stop is reached, the positioning device or the part to be positioned actuates a limit switch which stops the positioning drive. The limit switches must be accurately aligned since a faulty end stop can result, on one hand, in damaging the positioning device and, on the other hand, in overloading the positioning drive.
An integrated circuit for pulse-duration-modulated driving of direct-current motors is known from the in-house document "Silicon general, linear integrated circuits, voltage regulator with applications", Product Selection, 1982/83, Messrs. Astonik, Winzererstr. 47d, 8000 Munich 40, pages 111-118. The circuit is suitable for driving positioning device drive motors. The electric motor, which can be switched on by a control circuit via a driver circuit, is connected via a coupling to a part to be positioned and to an actual position value transmitter. The electric motor is switched on in dependence on the difference between a nominal position value and the actual position value until the system deviation drops below an adjustable value. The control circuit exhibits a connection, designated by "shut down", via which the driver circuit or the electric motor, respectively, can be switched off.